Process for the preparation of 4-quinolinones

Abstract

1,2,3,4-Tetrahydro-4-quinolinone of formula: ##STR1## are prepared from a 3-anilinopropionic acid of formula: ##STR2## which is treated successively with phosgene, phosgene in the presence of dimethylformamide, a Lewis acid or a strong acid, and a base. In the formula (I) and (II), R denotes a hydrogen atom, a halogen atom or an alkyl (1 to 4 carbon atoms) or alkoxy (1 to 4 carbon atoms) radical, and R 1 denotes a hydrogen atom or an alkyl radical (1 to 4 carbon atoms). The compounds of formula I are useful as intermediates in the production of known drugs.

We claim: 
     
       1. A process for the preparation of a 1,2,3,4-tetrahydro-4-quinolinone of the formula: ##STR8## in which R denotes a hydrogen atom, a halogen atom, a linear or branched alkyl group of 1 to 4 carbon atoms or a linear or branched alkoxy group of 1 to 4 carbon atoms, and R 1  denotes a hydrogen atom or a linear or branched alkyl group of 1 to 4 carbon atoms, which comprises treating a 3-anilinopropinoic acid of the formula: ##STR9## in which R and R 1  are as defined above, with phosgene to produce a product of the formula: ##STR10## in which R and R 1  are as defined above, reacting the said product with phosgene in the presence of dimethylformamide, to produce an acid chloride of the formula: ##STR11## in which R and R 1  are as defined above, treating the latter with a aluminum chloride in a suitable solvent to provide a product of formula: ##STR12## in which R and R 1  are as defined above, and hydrolysing the latter in the presence of an inert inorganic base to provide the 1,2,3,4-tetrahydro-4-quinolinone. 
     
     
       2. A process according to claim 1, in which the treatment with phosgene is performed in an organic solvent at a temperature between -10° and 150° C. 
     
     
       3. A process according to claim 2, in which the solvent is methylene chloride, 1,1,2-trichloroethane or dioxane. 
     
     
       4. A process according to claim 1, in which the hydrolysis is effected with sodium hydroxide in methanol. 
     
     
       5. A process according to claim 1, in which the product of formula: ##STR13## in which R and R 1  are as defined in claim 1, is prepared without isolation of the intermediate products. 
     
     
       6. A 1-chloroformyl-1,2,3,4-tetrahydro-4-quinolinone of the formula: ##STR14## in which R and R 1  are as defined in claim 1 provided that when R 1  is a hydrogen atom and R is other than a chlorine, bromine or fluorine atom in position 6. 
     
     
       7. A process according to claim 1, in which the aluminum chloride is used in a solvent chosen from a halogenated hydrocarbon, carbon disulphide, a nitroalkane and tetrachloroethylene.